The present invention relates to a semiconductor laser apparatus for use as a light source for reading signals from optical discs including CD (Compact Disc), CD-R (CD Recordable), DVD (Digital Versatile Disc) and DVD-R (DVD Recordable), and a method for manufacturing the same.
Conventionally, as an assembly structure of the semiconductor laser apparatus, there have been a frame type laser apparatus and a "PHgr"5.6 can type laser apparatus. Hereinbelow, the both apparatuses will be roughly described.
(1) Frame Type Laser Apparatus
(1) As shown in FIG. 5, the apparatus is structured such that on the top end of a metal lead frame 1 functioning as a lead terminal, a laser device 2 is mounted, and a mold resin 3 is used for molding. Part of a lead frame 1a positioned in both side portions is protruded from the lateral face of the mold resin 3 to lateral direction to constitute a plate-shaped portion 4, and one end face 4a of the plate-shaped portion 4 constitutes a reference plane (eyelet).
(2) As shown in FIG. 6, similar to the case (1), the apparatus is structured such that on the top end of a metal lead frame 5 functioning as a lead terminal, a laser device 6 is mounted, and a mold resin 7 is used for molding. In this case, one end face 7a of the mold resin 7 constitutes a reference plane (eyelet).
(2) "PHgr"5.6 Can Type Laser Apparatus
As shown in FIG. 7, the apparatus is structured such that a laser device 13 is mounted, via a heat sink (unshown), on a top face 12a of a stem 12 made of a circular metal block having a lead terminal 11 protruding from a bottom face, and after the laser device 13 is wire-bonded to the lead terminal 11, the laser device 13 and a wire (unshown) are covered with a protecting cap 14. In this case, the top face 12a of the stem 12 constitutes a reference plane. It is noted that reference numeral 15 denotes a cutting for positioning.
However, the above-described conventional assembly structures of the semiconductor laser apparatuses suffer a following problem.
(a) Frame Type Laser Device
(i) In the case of the frame type laser apparatus as shown in FIG. 5, the plate-shaped portion 4 protruding from the lateral face of the mold resin 3 has a constant thickness. Consequently, the area of the reference plane constituted by the one end face 4a of the plate-shaped portion 4 is determined by the thickness of the plate-shaped portion 4, which causes a problem that the strength of the reference plane is not fully secured and therefore heat dissipation is not sufficient.
(ii) In the case of the frame type laser apparatus as shown in FIG. 6, the reference plane is constituted by the one end face 7a of the mold resin 7. Consequently, there is a problem that the reference plane is lower in strength than that of a metal reference plane, and also the reference plane has expansion and shrinkage due to temperature change, which decreases accuracy as a reference plane. Further, there is another problem that heat dissipation is not fully secured as it is limited by the thickness of the lead frame 5.
(b) "PHgr"5.6 Can Type Laser Apparatus
As shown in FIG. 7, the reference plane and the heat dissipation portion are constituted by one plane of a metal block called the stem 12. Consequently, the strength and the heat dissipation of the reference plane is superior to those of the above-described frame type laser apparatus. However, since assembly is conducted by using the cap 14 for protecting the laser device 13 and the wire against the stem 12 made of a circular metal block, individual manufacturing is necessary whether in the case of a package itself or a final product, which decreases productivity and makes the apparatus unsuitable for mass collective production
Accordingly, it is an object of the present invention to provide a semiconductor laser apparatus capable of securing sufficient strength and heat dissipation of a reference plane and excellent in productivity, and to provide a method for manufacturing the same.
In order to achieve the above object, there is provided a semiconductor laser apparatus comprising: a base frame; a laser device mounting frame extensively disposed on one side of the base frame; and a lead frame extensively disposed on the other side of the base frame, all structured by one metal plate, wherein
the laser device mounting frame and the lead frame are bended so as to be opposite to each other against a plane of the base frame,
the base frame functions as a reference plane and a heat sinking base,
a semiconductor laser device is mounted on the laser device mounting frame, and
the lead frame becomes a lead terminal.
According to the above structure, the base frame functioning as a reference plane and as a heat sinking base is formed by bending a laser device mounting frame and a lead frame, which are structured together with the base from one metal plate, so that the laser device mounting frame and the lead frame are opposite to each other against the base frame. Therefore, the area of the reference plane and the heat sinking plane may be arbitrarily set by changing the bending position. This provides the frame type laser apparatus with high heat dissipation competing with that of "PHgr"5.6 can type laser apparatus.
Further, since the apparatus is a frame type laser apparatus, structuring plural sets of the laser device mounting frame, the base frame, and the lead frame in a multiple form enables collective packaging in large quantities, resulting in increase of productivity. Further, manufacturing of a final product may be performed in a multiple form, which enables further increase of productivity and enables manufacturing at low costs.
In one embodiment of the present invention, a configuration of the base frame is an approximate circle or an approximate oval partially in a shape of a circular arc.
According to this embodiment, the configuration of the base frame is an approximate circle or an approximate oval shape, which may provide strength and heat dissipation competing with those of the stem in the "PHgr"5.6 can type laser apparatus.
In one embodiment of the present invention, an optical axis of laser light from the semiconductor laser device mounted on the laser device mounting frame has an extension line traveling through an approximate center of the configuration of the base frame.
According to this embodiment, in addition to the fact that a configuration of the base frame is an approximate circle or partially a circular arc, the optical axis is not displaced when a mounting position is adjusted by rotating the base frame, which considerably simplifies adjustment of a mounting position.
In one embodiment of the present invention, at least a portion of the base frame to be the reference plane and the heat sinking base has an increased thickness.
According to this embodiment, a portion to be the reference plane and the heat sinking base has an increased thickness. This implements further increase of the strength and the heat dissipation of the reference plane.
In one embodiment of the present invention, on the base frame, there is formed a component protecting partition made of resin so as to surround the semiconductor laser device excluding a laser emitting side.
According to this embodiment, there is formed a component protecting partition so as to surround the semiconductor laser device. Therefore, though the apparatus is an open package, the semiconductor laser device, the wire, and the like are protected from careless touch. Further, the component protecting partition is structured not from a cap but a resin, so that collective packaging in large quantities is achieved.
In one embodiment of the present invention, the resin structuring the component protecting partition is formed with at least part of the laser device mounting frame and the lead frame being embedded therein, and the laser device mounting frame and the lead frame bended toward the base frame are fixed by the resin.
According to this embodiment, at least part of the laser device mounting frame and the lead frame are fixed by the resin. Consequently, the laser device mounting frame and the lead frame structured by bending one metal plate is free from flexion and the like, which may increase mounting rigidity.
In one embodiment of the present invention, a top end portion of the separated lead frame is inserted into the resin that constitutes the component protecting partition, and the top end portion is equipped with slip out preventing means for preventing slip out of the lead frame from the resin.
According to this embodiment, the lead frame electronically separated from the lead frame integrally formed with the base frame is fixed to a resin block of the component protecting partition. This increases mounting rigidity.
In one embodiment of the present invention, a positioning recess portion is provided on an outer circumferential edge of the base frame.
According to this embodiment, positioning for adjusting a mounting position by rotating the base frame is easily performed with the positioning recess portion on an outer circumferential edge.
In one embodiment of the present invention, the base frame, the laser device mounting frame and the lead frame that are formed integrally are formed from a copper plate or an iron plate whose surface is plated with gold or silver.
According to this embodiment, the base frame, the laser device mounting frame and the lead frame that are integrated are formed from a conductive metal plate made of copper or iron. This enables the lead frame to function as a lead terminal as it is. Further, plating the surface with gold or silver implements good wire-bonding of the semiconductor laser device to the lead frame.
Also, there is provided a method for manufacturing a semiconductor laser apparatus comprising the steps of:
forming plural groups of frames connected by a casing frame and a tie-bar from one metal plate, the group composed of a base frame, a laser device mounting frame extensively disposed on one side of the base frame, a first lead frame extensively disposed on the other side of the base frame, and a second frame separated from the first lead frame;
bending the laser device mounting frame and the first lead frame in each group so as to be opposite to each other against the base frame;
mounting the semiconductor laser device on the laser device mounting frame in each group, and then wire-bonding the semiconductor laser device to the first and second lead frames; and
forming a component protecting partition from resin on the base frame in each group so as to surround the semiconductor laser device excluding a laser emitting side.
According to the above method, plural groups of frames consisting of a laser device mounting frame, a base frame, first and second frames connected via a casing frame and a tie-bar are formed from one metal plate, and each group simultaneously undergoes the steps of forming, mounting of a semiconductor laser device, wire-bonding, and resin-molding. This enables collective mass production of a plurality of semiconductor laser apparatuses having high strength and heat dissipation of the reference plane in the form of final products, thereby implementing increase of productivity and reduction of costs.
In one embodiment of the present invention, forming of frames from one metal plate is conducted by stamping with use of a mold.
According to this embodiment, forming of the frames becomes easier and productivity is further increased.
In one embodiment of the present invention, the method further comprises the step of providing a groove in a bending portion of each frame in advance of the step of bending the laser device mounting frame and the first lead frame.
According to this embodiment, bending of the laser device mounting frame and the first lead frame in the forming process is simplified, which implements further increase of productivity.
In one embodiment of the present invention, bending of the laser device mounting frame and the first lead frame is conducted with use of a mold.
According to this embodiment, bending of the laser device mounting frame and the first lead frame in a plurality of groups is collectively conducted with use of a mold, which implements increase of productivity.
In one embodiment of the present invention, the method further comprises the step of attaching a metal plate to at least a portion of the base frame to be a reference plane and a heat sinking base, the metal plate having a form identical to the portion.
According to this embodiment, a portion to be the reference plane and the heat sinking base is given an increased thickness. This further increases strength and heat dissipation of the reference plane.
In one embodiment of the present invention, the method further comprises the step of decreasing a thickness of a portion other than the portion of the base frame to be the reference plane and the heat sinking base, a thickness of the laser device mounting frame, and a thickness of the first lead frame by pressing.
According to this embodiment, processing for increasing the thickness in order to increase strength and heat dissipation of the reference plane for plural groups of frames is achieved by one operation of pressing. Therefore, productivity is increased more than the case of attaching a metal plate as shown in the antecedent embodiment.